1. Field of the Invention
The present invention relates to a valve adapted to dispense water and air, and suitable for equipping installations for spraying water under pressure, in particular for making artificial snow.
2. Description of the Related Art
Current snow-making installations for making artificial snow incorporate much technological progress that has made it possible to improve their effectiveness and their efficiency by making better use of weather conditions.
This applies, in particular, to the spray devices equipping such snow-making installations, for making artificial snow, and that can operate at very different water and air flow-rates so as to take better advantage of weather conditions.
Such flow-rate regulation is usually implemented by means of valves adapted to dispense water and air, and that equip the feed circuits connected to such spray devices.
A valve of that type that is currently used in snow-making installations is described, for example, in Document FR-2 573 854.
That valve consists of a device in the form of a slide valve connected to the water and air feed pipes of the installation. A single cylindrical slide is driven to slide inside a chamber provided in the valve body, in order to control the water, air, and emptying flow-rates.
Although it is particularly advantageous and effective, that valve suffers from the drawback of having only a single emptying point provided in its water circuit downstream from the closure point. In very cold weather, any water present in the air circuit can then cause the spray device situated downstream to freeze. Another drawback is that water might leak into the air in the event of failure of the seals because the bore is common to both circuits.
Valves are also known that are of a universal type, adapted to dispense water, or possibly air, in installations for spraying water under pressure.
Such valves, e.g. as described in Document FR-2 795 494, are, in practice, effective and flexible in use, but they are relatively voluminous when they are combined, and they make it necessary for the water and air circuits to be managed independently, which is relatively complex.
In addition, that increases the number of control members and associated components, in particular hydraulic and electrical connectors, with ensuing economic consequences.
In addition, with the increase in the size of snow-making networks, new problems are arising:                the air network can, in certain places, trap large quantities of water; that water can constitute a major risk of the snow-makers freezing; and        the water network can also contain air that might disturb the regulation of the valves.        
Neither of the above-mentioned systems makes it possible in satisfactory manner to solve the problems relating both to bleeding the circuits, i.e. to purging the upstream circuits on opening the valve, and also to emptying, i.e. to removing the fluid contained in the downstream circuit on closing the valve.